Switch device

A switch device (35) is provided that ensures formation of a communicable area by a coil antenna (17). The switch device includes an ignition switch (30) operated by an operator for driving an engine starter (18), a decorative cap (32) arranged to surround the ignition switch and having an ornamental surface (32a), and the coil antenna arranged adjacent to the decorative cap for transmitting a transponder-driving radio wave. The decorative cap includes a transmittable area (42) that can transmit the transponder-driving radio wave therethrough. The transmittable area is formed in a part of the decorative cap excluding the ornamental surface.